Let's dive into this subtraction. We'll start with 439242 and subtract 12889 from it.

Step 1: We'll start by subtracting the digit 9 and the borrow 0 from 2 in column 1 and get -7.
We add -7 to 10 and get 3 as the first digit of the result.

Step 2: We'll start by subtracting the digit 8 and the borrow 1 from 4 in column 2 and get -5.
We add -5 to 10 and get 5 as the next digit of the result.

Step 3: We'll start by subtracting the digit 8 and the borrow 1 from 2 in column 3 and get -7.
We add -7 to 10 and get 3 as the next digit of the result.

Step 4: We'll start by subtracting the digit 2 and the borrow 1 from 9 in column 4 and get 6.
6 is the next digit of our result.

Step 5: We'll start by subtracting the digit 1 and the borrow 0 from 3 in column 5 and get 2.
2 is the next digit of our result.

Step 6: We'll start by subtracting the digit 0 and the borrow 0 from 4 in column 6 and get 4.
4 is the next digit of our result.

So, 439242 - 12889 = 426353.